update label in Area Color Mapping section to reflect whether it is a…

…ctive

src/gui/gtk.c

@@ -4132,6 +4132,7 @@ void dt_gui_new_collapsible_section(dt_gui_collapsible_section_t *cs,
   GtkWidget *destdisp_head = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_BAUHAUS_SPACE);
   GtkWidget *header_evb = gtk_event_box_new();
   GtkWidget *destdisp = dt_ui_section_label_new(label);
+  cs->label = destdisp;
   dt_gui_add_class(destdisp_head, "dt_section_expander");
   gtk_container_add(GTK_CONTAINER(header_evb), destdisp);
 
@@ -4161,6 +4162,16 @@ void dt_gui_new_collapsible_section(dt_gui_collapsible_section_t *cs,
                    G_CALLBACK(_collapse_expander_click), cs);
 }
 
+void dt_gui_collapsible_section_set_label(dt_gui_collapsible_section_t *cs,
+                                          const char *label)
+{
+  if (!cs || !cs->label || !label)
+    return;
+  gtk_label_set_text(GTK_LABEL(cs->label), label);
+//  dt_control_queue_redraw_widget(cs->label);
+  dt_control_queue_redraw();
+}
+
 gboolean dt_gui_long_click(const int second,
                            const int first)
 {

src/gui/gtk.h

@@ -155,6 +155,7 @@ typedef struct _gui_collapsible_section_t
   gchar *confname;      // configuration name for the toggle status
   GtkWidget *toggle;    // toggle button
   GtkWidget *expander;  // the expanded
+  GtkWidget *label;	// the label containing the section's title text
   GtkBox *container;    // the container for all widgets into the section
   struct dt_action_t *module; // the lib or iop module that contains this section
 } dt_gui_collapsible_section_t;
@@ -514,6 +515,9 @@ void dt_gui_new_collapsible_section(dt_gui_collapsible_section_t *cs,
                                     const char *label,
                                     GtkBox *parent,
                                     struct dt_action_t *module);
+// update the collapsible section's label text
+void dt_gui_collapsible_section_set_label(dt_gui_collapsible_section_t *cs,
+                                          const char *label);
 // routine to be called from gui_update
 void dt_gui_update_collapsible_section(dt_gui_collapsible_section_t *cs);
 

src/iop/channelmixerrgb.c

@@ -596,6 +596,18 @@ void init_presets(dt_iop_module_so_t *self)
                              self->version(), &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_SCENE);
 }
 
+static gboolean _area_mapping_active(const dt_iop_channelmixer_rgb_gui_data_t *g)
+{
+  return g && g->spot_mode && dt_bauhaus_combobox_get(g->spot_mode) != DT_SPOT_MODE_MEASURE &&
+    ((g->lightness_spot && dt_bauhaus_slider_get_val(g->lightness_spot) != 50.0f) ||
+     (g->hue_spot && dt_bauhaus_slider_get_val(g->hue_spot) != 0.0f) ||
+     (g->chroma_spot && dt_bauhaus_slider_get_val(g->chroma_spot) != 0.0f));
+}
+
+static const char *_area_mapping_section_text(const dt_iop_channelmixer_rgb_gui_data_t *g)
+{
+  return _area_mapping_active(g) ? _("area color mapping (active)") : _("area color mapping");
+}
 
 static gboolean _get_white_balance_coeff(struct dt_iop_module_t *self,
                                          dt_aligned_pixel_t custom_wb)
@@ -3872,6 +3884,7 @@ void gui_update(struct dt_iop_module_t *self)
   g->last_bb_temperature = d->temperature;
 
   dt_gui_hide_collapsible_section(&g->cs);
+  dt_gui_collapsible_section_set_label(&g->csspot, _area_mapping_section_text(g));
   dt_gui_update_collapsible_section(&g->csspot);
 
   g->spot_RGB[0] = 0.f;
@@ -4577,7 +4590,7 @@ void gui_init(struct dt_iop_module_t *self)
   dt_gui_new_collapsible_section
     (&g->csspot,
      "plugins/darkroom/channelmixerrgb/expand_picker_mapping",
-     _("area color mapping"),
+     _area_mapping_section_text(g),
      GTK_BOX(self->widget),
      DT_ACTION(self));
 
@@ -4685,6 +4698,7 @@ void gui_init(struct dt_iop_module_t *self)
   gtk_box_pack_start(GTK_BOX(hhbox), GTK_WIDGET(vvbox), TRUE, TRUE, DT_BAUHAUS_SPACE);
 
   gtk_box_pack_start(GTK_BOX(g->csspot.container), GTK_WIDGET(hhbox), FALSE, FALSE, 0);
+  dt_gui_collapsible_section_set_label(&g->csspot, _area_mapping_section_text(g));
 
   GtkWidget *first, *second, *third;
 #define NOTEBOOK_PAGE(var, short, label, tooltip, section, swap, soft_range, sr_min, sr_max) \